1. Field of the Invention
The present invention relates to an arrangement of conductors for power lines using alternating current, and more particularly, to rotating electric machine, electric apparatus, power supply apparatus, power conversion apparatus and power transmission lines having power lines using alternating current.
2. Description of the Related Art
When arranging parallelly a plurality of conductors to transmit alternating currents, the method of arranging the conductors has not been satisfactorily taken into consideration of conventional power lines. For example, in electric apparatus having power lines in which six conductors transmitting, respectively, to-and-fro currents of balanced three phases U, V and W are arranged in a row, the conductors are arranged in an order of +U, xe2x88x92V, +W, xe2x88x92U, +V and xe2x88x92W phases so that the phase difference between the currents flowing through adjacent conductors is small.
In the above case, since the magnetic field induced into a conductor by a current flowing through the other conductor is large, it is possible that the loss by an eddy current produced in the conductor is large, resulting in necessity of more devices and much cost for cooling the conductors. Further, it is possible that the electrical efficiency of the power lines is reduced or that it is required to make larger the distance between adjacent conductors so that the size of the power lines becomes larger.
An object of the present invention is to provide power lines having conductor arrangement capable of reducing the above loss so that the power efficiency is made higher thereby requiring less devices and less cost for cooling the conductors.
Another object of the present invention is to provide rotating electric machines, electric apparatus, power supply apparatus, power conversion apparatus and power transmission lines of large electric currents, which use the above power lines thereby increasing the power efficiency and requiring less cost of devices for cooling the conductors.
In order to achieve the above object, in the power lines of the present invention in which three or more conductors transmitting alternating currents of different phases are disposed parallelly with each other, the conductor arrangement is determined such that from all the combinations in arrangement of the conductors, which are obtained by exchanging every two of the conductors, those combinations are first selected in which the sum of the phase differences between the currents flowing through every adjacent two conductors is maximum and then from those selected combinations, one combination is selected in which the smallest one of the values of the phase differences between the currents flowing through every adjacent conductors is largest and the conductor arrangement as determined is corresponding to that in the selected one combination.
Further, in the power lines having 2n conductors respectively transmitting the to-and-fro currents of n-phase alternating current and arranged parallelly with each other in a row, the conductors are arranged such that the phase differences between the currents flowing through every adjacent two conductors are in an order of the phase angles 180, (180xe2x88x92180/n), 180, (180xe2x88x92180/n), . . . 180 and (180xe2x88x92180/n) degrees, successively, from one end of the row.
Further, in the power lines including six conductors transmitting the to-and-fro currents of +U, +V, +W, xe2x88x92U, xe2x88x92V and xe2x88x92W phases of 3-phase alternating current and disposed parallelly with each other in a ring shape, the phase differences between the currents flowing through every adjacent conductors are in an order of the phase angles 180, 120, 120, 180, 120, and 120 degrees successively.
Further, in the power lines having 2n conductors transmitting respective phases of 2n-phase alternating currents and disposed parallelly with each other in 2 rows and n stages, the conductors are arranged such that the distance between adjacent conductors in the same stage is larger than the distance between adjacent conductors in the same row, the phase difference between the currents passing through every adjacent conductors in the same row is 180 degrees and the phase difference between the currents passing through every adjacent conductors in the same stage is (180xe2x88x92180/n) degrees.
Further, the present invention provides an apparatus such as rotating electric machine, electric apparatus including power generator, power supply apparatus, power conversion apparatus and power transmission line, which requires to handle a large current, and includes the power lines having any of the above-mentioned conductor arrangements.
By the above arrangement, the present invention is capable of reducing the whole loss of the conductors, increasing the power efficiency and requiring less devices for cooling the conductors thereby decreasing the cost for the devices.